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+# How to Use the mruby Debugger
+
+copyright (c) 2014 Specified Non-Profit Corporation mruby Forum
+
+## 1. Summary
+
+This file documents the mruby debugger ('mrdb') methods.
+
+## 2 Debugging with mrdb
+
+## 2.1 Building mrdb
+
+The trunk of the mruby source tree, with the most recent mrdb, can be checked out with the following command:
+
+```bash
+$ git clone https://github.com/mruby/mruby.git
+```
+
+To run the `make` command:
+
+```bash
+$ cd mruby
+$ make
+```
+
+By default, the `make` command will install the debugger files into mruby/bin.
+
+You can add the path for mrdb on your host environment with the following command:
+
+```bash
+$ echo "export PATH=\$PATH:MRUBY_ROOT/bin" >> ~/.bashrc
+$ source ~/.bashrc
+```
+
+`*MRUBY_ROOT` is the directory in which mruby source code will be installed.
+
+To confirm mrdb was installed properly, run mrdb with the `--version` option:
+
+```bash
+$ mrdb --version
+mruby 2.1.2 (2020-08-06)
+```
+
+## 2.2 Basic Operation
+
+### 2.2.1 Debugging mruby Script Files (rb file) with mrdb
+
+To invoke the mruby debugger, just type `mrdb`.
+
+To specify the script file:
+
+```bash
+$ mrdb [option] file name
+```
+
+For example: Debugging sample.rb
+
+```bash
+$ mrdb sample.rb
+```
+
+You can execute the shell commands listed below:
+
+|command|description|
+|:-:|:--|
+|run|execute programs|
+|step|execute stepping|
+|continue|execute continuing program|
+|break|configure the breaking point|
+|delete|deleting the breaking points|
+|disable|disabling the breaking points|
+|enable|enabling the breaking points|
+|info breakpoints|showing list of the breaking points|
+|print|evaluating and printing the values of the mruby expressions in the script|
+|list|displaying the source cords|
+|help|showing help|
+|quit|terminating the mruby debugger|
+
+### 2.2.2 Debugging mruby Binary Files (mrb file) with mrdb
+
+You can debug the mruby binary files.
+
+#### 2.2.2.1 Debugging the binary files
+
+* notice
+To debug mruby binary files, you need to compile mruby files with option `-g`.
+
+```bash
+$ mrbc -g sample.rb
+```
+
+You can debug the mruby binary files with following command and the option `-b`.
+
+```bash
+$ mrdb -b sample.mrb
+```
+
+Then you can execute all debugger shell commands.
+
+#### Break Command
+
+You can use any breakpoint to stop the program by specifying the line number and method name.
+The breakpoint list will be displayed after you have set the breakpoint successfully.
+
+Usage:
+
+```
+break [file:]linenum
+b [file:]linenum
+break [class:]method
+b [class:]method
+```
+
+The breakpoint will be ordered in serial from 1.
+The number, which was given to the deleted breakpoint, will never be given to another breakpoint again.
+
+You can give multiple breakpoints to specified the line number and method.
+Be ware that breakpoint command will not check the validity of the class name and method name.
+
+You can get the current breakpoint information by the following options.
+
+breakpoint breakpoint number : file name. line number
+
+breakpoint breakpoint number : [class name,] method name
+
+#### Continue Command
+
+Usage:
+
+```
+continue [N]
+c [N]
+```
+
+N: the next breakpoint number
+
+When resuming the program, it will stop at breakpoint N (N-1 breakpoint will be ignored).
+
+When you run the `continue` command without specifying N, the program will be stopped at the next breakpoint.
+
+Example:
+
+```
+(foo.rb:1) continue 3
+```
+
+This will resume the program and stop it at the third breakpoint.
+
+#### Delete Command
+
+This will delete the specified breakpoint.
+
+Usage:
+
+```
+delete [breakpoint-no]
+d [breakpoint-no]
+```
+
+breakpoint-no: breakpoint number
+
+Example:
+
+```
+(foo.rb:1) delete
+```
+
+This will delete all of the breakpoints.
+
+```
+(foo.rb:1) delete 1 3
+```
+
+This will delete the breakpoint at 1 and 3.
+
+#### Disable Command
+
+This will disable the specified breakpoint.
+
+Usage:
+
+```
+disable [breakpoint-no]
+dis [breakpoint-no]
+```
+
+reappointing: breakpoint number
+
+Example:
+
+```
+(foo.rb:1) disable
+```
+
+Use `disable` if you would like to disable all of the breakpoints.
+
+```
+(foo.rb:1) disable 1 3
+```
+
+This will disable the breakpoints at 1 and 3.
+
+#### Enable Command
+
+This will enable the specified breakpoints.
+
+Usage:
+
+```
+enable [breakpoint-no]
+e [breakpoint-no]
+```
+
+breakpoint-no: breakpoint number
+
+Example:
+
+```
+(foo.rb:1) enable
+```
+
+Enabling all breakpoints
+```
+(foo.rb:1) enable 1 3
+```
+
+Enabling the breakpoint 1 and 3
+
+#### eval command
+
+Evaluating the string as source code and printing the value.
+
+Same as print command, please see print command.
+
+#### help command
+
+Displaying the help message.
+
+Usage:
+
+```
+help [command]
+h [command]
+```
+
+Typing `help` without any options will display the command list.
+
+#### Info Breakpoints Command
+
+Displaying the specified breakpoint information.
+
+Usage:
+
+```
+info breakpoints [breakpoint-no]
+i b [breakpoint-no]
+```
+
+breakpoint-no: breakpoint number
+
+Typing "info breakpoints" without ant option will display all breakpoint information.
+Example:
+
+```
+(sample.rb:1) info breakpoints
+Num     Type           Enb What  
+1       breakpoint     y   at sample.rb:3                      -> file name,line number
+2       breakpoint     n   in Sample_class:sample_class_method -> [class:]method name
+3       breakpoint     y   in sample_global_method
+```
+
+Displaying the specified breakpoint number:
+
+```
+(foo.rb:1) info breakpoints 1 3
+Num     Type           Enb What  
+1       breakpoint     y   at sample.rb:3  
+3       breakpoint     y   in sample_global_method
+```
+
+#### List Command
+
+To display the code of the source file.
+
+Usage:
+
+```
+list [filename:]first[,last]
+l [filename]:first[,last]
+```
+
+first: the opening row number
+last : the closing row number
+
+When you specify the `first`, but not the `last` option, you will receive 10 rows.
+When you do not specify both the `first` and `last` options, you will receive the next 10 rows.
+
+Example:
+
+```
+Specifying file name and first row number
+sample.rb:1) list sample2.rb:5
+```
+
+Specifying the file name and the first and last row number:
+
+```
+(sample.rb:1) list sample2.rb:6,7
+```
+
+#### Print Command
+
+Evaluating the string as source code and printing the value.
+
+Usage:
+
+```
+print [expr]
+p [expr]
+```
+
+expr: expression
+
+The expression is mandatory.
+The displayed expressions will be serially ordered from 1.
+If an exception occurs, the exception information will be displayed and the debugging will be continued.
+
+Example:
+
+```
+(sample.rb:1) print 1+2
+$1 = 3
+(sample.rb:1) print self
+$2 = main
+```
+
+Below is the case of the exception:
+
+```
+(sample.rb:1) print (1+2
+$1 =  SyntaxError: line 1: syntax error, unexpected $end, expecting ')'
+```
+
+#### Quit Command
+
+Quitting the debugger.
+
+Usage:
+
+```
+quit
+q
+```
+
+#### Run Command
+
+Running the program and stopping at the first breakpoint.
+
+Usage:
+
+```
+run
+r
+```
+
+#### Step Command
+
+This will run the program step by step.
+When the method and the block are invoked, the program will be stop at the first row.
+The program, which is developed in C, will be ignored.